In satellite communications systems it is important to control the uplink sidelobe levels to minimize interaction between the terminal and its network and another network operating at or very close to the same frequency. In mobile earth terminals with moderate gain antennas and uplink power levels, the interference problem is exacerbated by the generally high sidelobes that are associated with illuminations that optimize power transfer to the radiating field.
Many mobile earth terminals, and other applications, use active electronically steered arrays (AESAs) for the communications antennas. To address the interference problem, there have been several attempts to reduce AESA sidelobe levels while maintaining illumination efficiency; however these attempts have not been successful. For example, attempts have been made to use non-uniform amplitude illumination distributions (e.g., Taylor illumination) and to use phase tapering techniques. Non-uniform amplitude distributions result in lower radiated signal power levels due to the inherent inefficiency of the amplitude shaping function. Phase tapering is unreliable, being difficult to implement, and also suffers from reduced radiated signal power levels.